This invention uses the Double Cap concept of my “Multiple Cap Seal for Containers” U.S. Pat. No. 5,295,599 issued Mar. 22, 1994.
Another area of this application relates to the wiping mechanism which was described in my Invention Disclosure “Screw Cap with Sealing/Wiping Diaphragm” dated Feb. 11, 1994 and a second version dated and filed Jan. 11, 1996 Disclosure Doc. 390080 with the Patent Office.
Another area relates to a one piece tethered cap and tube as described by my invention disclosure “One Piece Tamper Resistant Cap and Vial” Disclosure Doc. No. 384710 dated Oct. 10, 1995.
Screw cap vials for micro centrifuge tubes have been used in the medical disposable industry for many years. Their continued acceptance comes from the fact that they provide the best leak proof design for centrifugation, heating and freezing of sample fluids. Their disadvantages are primarily due to the fact that they are individually molded and usually require the assembly of an O-ring or liner to increase the sealing caps effectiveness. The major problem relates to a cost issue, which makes this product (tube and cap) approximately 10 times the cost of an integrally molded cap micro centrifuge tube. Prior art has also demonstrated that thread seals alone are not dependable and the use of different materials in the construction of caps, seals and containers has caused leakage problems. This is due to the thermal expansion and contraction rates associated with different materials during testing and/or storage at high and low temperatures.
Another disadvantage of the prior art closures is the potential for contamination of not only the added O-ring elastomer used as a sealing ring in the cap but also the colorant used in the molding of the plastic closures. The fact that caps can also get misplaced or put back onto another vial by accident causes other contamination occurrences. This last problem has been addressed in the industry by the addition of a tethered strap to hold the cap to the tube with an additional part and increased cost. An example of this would be U.S. Pat. No. 4,753,358 by Virea which describes how this tether can be created as a separate piece and be used to hold the cap and tube together as a one piece assembly.
It is also known in the industry that chemical resistance of containers and closures is of the utmost importance. While most plastic assemblies are made from polypropylene or polyethylene, these materials still lack the chemical resistance and temperature requirements for all applications. It It is known that TEFLON (registered trademark of Dupont) and its injection moldable grades (PFA, FEP, TEFZEL etc.) are far superior for these uses but that they lack the mechanical properties necessary to hold the close tolerance for these applications. This new invention helps to solve these and many more problems associated with the prior art.
Another problem arises when the fluid samples are required to be accessed in the same container many times over or when the caps must remain off for extended periods. In both cases the fluids are exposed to atmospheric air exchanges, which can cause contamination, evaporation, condensation and/or aging of the fluid sample, which can affect the accuracy of any analysis being conducted on the specimens. The new invention addressed these concerns by limiting air exchanges yet still allowing easy access to the fluid contents.
This invention also relates to closures that promote sterile air venting and filtering of the container without the use of secondary plugs or permeable membranes used to maintain equilibrium between atmosphere and the inside of the container as illustrated in U.S. Pat. Nos. 2,186,908 & 5,595,907. This is accomplished by injection molding small (i.e. 5 to 50 micron) textured air channel vents into the sealing surface of the closure and/or container.
This invention also relates to a one-piece tamper evident closure with tethered container. Unlike existing snap on, snap off or snap on, screw off tamper evident closures as taught by U.S. Pat. Nos. 5,190,178, and 5,267,661, and 5,456,376 this invention has many advantages. The most apparent is the low cost one-piece injection molded assembly. By molding as one piece, no orientation of the cap to its mating sealing threads during assembly is required. It only requires a downward axial force to engage a sealing surface. There also will be no fit or sealing problems due to multi-cavity processing, material shrinkage and/or tolerance problems because the closure and its container are being molded in the same tool at the same time with the same material (i.e. lot no.) unlike existing art under the same exact processing parameters. (i e.: time, pressure, heat, humidity, etc.).
In addition, this invention also addresses the similar problems found with fitments as described by U.S. Pat. Nos. 5,174,465 and 5,348,184 which have many deficiencies. Even though these closures are mechanically attached to their fitment during the molding process, they lack the integral tether to keep its potentially contaminated cap with its container after each use. They also include internal threads which are known in the medical industry to provide a means for capture of liquid particulates while also providing recesses for contaminants to solidify thus, effecting the sealing capability and contamination problems during re-use. Also the uses of tamper evident foil seals are seals are used for added sealing capability that adds additional costs and labor to these closures.
In addition, most containers are accessed with the use of a standard disposable pipette tip that is attached to a hand held pipetter in the medical industry. In normal operation when the tip is inserted into the fluid and the precise amount of sample is drawn inside the tip for transportation to another location, there exists a thin film of residue fluid attached to the outside of the tip. This is due to the surface tension of the material used to manufacture the pipette tip and the fluid characteristic of the sample. Common practice in the industry suggests that the outside of these tips be wiped clean with a KIMWIPE tissue prior to the dispensing cycle. This however, causes the following problems: 1) Requires the contact and disposal of an additional product (i.e. tissue); 2) Puts the user at risk while transporting highly infectious or radioactive fluids; 3) Reduces the amount of specimen that can be analyzed; 4) Adds cost and additional time necessary to perform dispensing. Some manufactures have added silicone to the polypropylene tip material (i.e. siliconized pipette tips) at additional cost to help reduce this problem, but still have not eliminated it. The thin film that is left on the outside of the tip usually combines to form small fluid droplets and could:                Affect the accuracy of the calibrated sample if they combine with the precise volume that is being dispensed by the inside of the tip. This can occur if the tip touches the sides of the receiving container leaving its droplets to combine with the sample being transferred;        Droplets can fall from the tip while being transported in or out of the container;        Droplets can migrate to the tip's dispensing end and combine with the precision amount of internal fluid to affect the dispensing accuracy;        Leads to cross-contamination or contamination in general, if any of the outside fluid were to contact any surface or thing (i.e. radioactive material or volatile fluids);        In applications where samples are very small and precious any additional fluid that would be wasted by being attached to the outside surface of the tip could become very costly and would allow fewer test specimens to be examined.        
This new invention addresses all of these concerns by providing an injection molded wiper as part of the closure to eliminate any and all residue occurring during transferring of fluids during liquid pipetting.
Another recurring problem with micro centrifuge tubes is the requirement to filter aqueous samples for clarification, particulate removal and/or sample preparation prior to the liquid being dispensed into the tube for testing. Prior art suggests the use of an additional filter assembly as manufactured by Gelman or Fisher Scientific be installed into the tubes opening to act as a funnel filtering all incoming fluids before entering the container. After the container is filled, this filter assembly must then be discarded and the tube can then be capped for storage or further testing. This not only becomes time consuming but the additional filter assembly ads cost and potential problems with contamination and disposal. The new invention addresses these problems with a one-piece design.
Another problem arises when smaller more delicate tissue samples, used by histologists, are usually first put into small biopsy bags or separate open-mesh capsules then submersed into histological solvents, in a separate container, for storage. This new invention helps to reduce the number of parts and tasks associated with the technician's labor hours and tissue handling time by creating a new storage closure that addresses these issues.
Accordingly, there is a need for a simple cap closure that addresses all of these problems by reducing the time necessary to perform these operations, minimize the contamination problems, prolongs sample life and reduces the manufacturing costs.
For a better understanding of the invention and how this new cap closure overcomes these disadvantages, reference is made to the following Summary, Preferred Embodiments, Detailed Description and Drawings.